(a) Field of the Invention
With the progress of technologies, life is becoming more and more convenient. Most of the household electrical appliances, such as television, stereo sets, video recorders, compact disk players, etc., are equipped with remote controllers. By pressing push button keys on the remote controllers, the corresponding electrical appliance will be actuated to perform the designated function. For telecommunication equipment, such as the telephones, mobile phones, facsimile machines, etc., they are mostly controlled by means of push button keys as well. With the development of integrated circuits, in order to save time in flipping through telephone directories or name cards, telephones and facsimile machines, for instance, have speed dialing and repeat functions, etc. The user only needs to pre-set telephone or facsimile numbers in the equipment, and can then press a certain key or certain keys to accomplish automatic dialing. This is indeed convenient and saves time.
However, as telephone and facsimile numbers are often difficult to memorize, if the wrong key is pressed and the wrong pre-set numbers are automatically dialed, it will be a waste of time and an increase in telephone and facsimile expenses. For facsimile machines, children may play with the push buttons and trigger the automatic dialing function. For mobile phones, the wrong key may be pressed when held in the hand since a little pressure on the key will trigger the designated function. Therefore, it is desirable to have a device that can prevent inadvertent pressing of push button keys of equipment as mentioned above.
(b) Description of the Prior Art
Some existing mobile phones are provided with a liftable or slidable cover. However, as such a cover has to be completely lifted to allow access to the push buttons, and is connected to both sides of the bottom portion of the phone body by hinges or cooperating coupling members, after a period of use, the connection between the phone body and the cover will become loosened due to constant friction. Therefore, most of the existing mobile phones are not equipped with liftable or slidable covers, and the problem of inadvertent pressing the push button keys remains unsolved.